Ellie Goulding, Chris Packham and Imelda Staunton are among the stars who appear in a video for Extinction Rebellion devised by Richard Curtis.
The short film outlines the demands of the group and asks governments where is their plan to tackle climate change.
It also features Jaime Winstone, Daisy Lowe, Jim Carter, Stephen Frears and Simon Amstell, as well as children from as young as eight as they demand a plan to address the crisis.
The concept for the film was developed by Love Actually director Curtis, and was shot and produced by Rankin – an agency headed up by the British photographer of the same name.
Packham said: “Time has run out. It’s act now or face almost unimaginable consequences for life on Earth.
“So if the drivers of change are asleep at the wheel, it’s time to shake and wake them with one hand and to empower ourselves to make our own differences with the other.”
Winstone added: “This film must reach governments and ring the alarm bell to act now on the climate crisis we are all living in. We must all ask of them #WhereIsYourPlan.”